The present disclosure relates to a thermal-transfer laminate film, a thermal-transfer sheet, and an image forming apparatus including the thermal-transfer laminate film and the thermal-transfer sheet.
From the past, for image protection, a thermal-transfer image protection layer formed of a thermoplastic resin has been laminated on an image formed on a printing paper, that is, an image formed by, for example, a sublimation-type thermal-transfer method that uses a sublimation dye or a thermal diffusion dye.
As a lamination method of a thermal-transfer image protection layer, a method of performing thermocompression bonding on an ink image using a heating roller is known. There is also known a method of structuring an image laminate film including a base film and a thermal-transfer image protection layer that is formed of a thermoplastic resin and formed on the base film and transferring only the heated part of the thermal-transfer image protection layer onto an image using a thermal head or the like, that is, a method that uses a thermal-transfer laminate film (see, for example, Japanese Patent Application Laid-open No. Sho 58-147390, Japanese Patent Application Laid-open No. Sho 60-23096, and Japanese Patent Application Laid-open No. Sho 60-204397).
By laminating the thermal-transfer image protection layer on a formed image as described above, an improvement of an image preservation stability can be expected, for example.
In addition, an untransferring release layer may be interposed between the base film and the image protection layer. The untransferring release layer is provided for enhancing a detachability of the base film and the image protection layer during thermal transfer. In other words, when the image protection layer is thermally transferred onto an ink image using a thermal energy of the thermal head, the adjacent image protection layer is positively peeled off at an interface between the image protection layer and the untransferring release layer so as to transfer only the image protection layer onto a printing paper.
For example, in Japanese Patent Application Laid-open No. 2000-108526, an ionomer of a fluorine-modified acrylic resin is used on an untransferring release layer to enhance adhesiveness between the untransferring release layer and a base film and obtain a favorable detachability of an image protection layer.